The present invention concerns a card of the smart card type comprising a substantially rectangular flat support.
A card of the smart card type is a card with standardised dimensions and functions comprising one or more integrated circuits with electrical contacts. Such a card is described for example in the document WO 99/38118.
This card C comprises, as shown in FIG. 1, a rectangular flat support 10 having two longitudinal edges 18 and 20 substantially parallel to each other, and two so-called respectively front and rear transverse edges 22 and 24 substantially parallel to each other, perpendicular to the longitudinal edges 18 and 20 and with a length shorter than that of said longitudinal edges.
The support 10 is intended to receive, on a so-called functional portion 14, situated on the front side 12 of said support and in the vicinity of the front transverse edge 22, a series of electrical contact areas 16 associated with an electronic microcircuit (not depicted). The electrical contact areas 16 are used to connect this electronic microcircuit to an operating circuit belonging to a device comprising for example a connector in which the card is placed so that its contact areas cooperate with contacts of the connector.
Moreover, the support has a substantially rectangular slit F surrounding the functional portion, so as to delimit a mini-card MC detachable from the support 10 and connected thereto by at least two, and in general three, links B1, B2 and B3. The mini-card MC thus delimited has an outline substantially parallel to that of the support 10 of the card C.
Two of the three links, referred to as the top B2 and bottom B3 links, extend respectively from a longitudinal edge 26, 28 of the mini-card MC in the direction of the immediately adjacent longitudinal edge 18, 20 of the support 20. The top B2 and bottom B3 links each comprise two grooves opposite each other on each face of the support, making these links able to withstand bending and twisting forces whilst making it possible to detach the mini-card MC from the support 20 by pressure.
The third link B1, referred to as the large lateral link, generally extends from the transverse edge 30 of the mini-card closest to the front transverse edge 22 of the support 10 in the direction of this front transverse edge 22.
By virtue of these links, it is possible to convert the card C, which is for example a SIM (Subscriber Identity Module) card intended to be used in a portable telephone, into a SIM mini-card intended to be used in a smaller portable telephone, by detaching the mini-card MC from the card C by breaking the links for example by vertical manual pressure perpendicular to the plane of the support 10.
This design makes it possible to provide the user with a card that he can use according to one other of the formats (card or mini-card) according to the receiving device into which he has to insert the card.
In a known manner according to the document WO 99/38118, the section of the upper groove (that is to say the one situated on the front side 12 of the support 10) of each of the top and bottom links B2, B3 in a plane perpendicular to the plane of the support 10 and parallel to the transverse edges 22, 24 thereof is substantially trapezoidal in shape with its bases parallel to the plane of the support 10. This allows the top and bottom links to withstand standardised mechanical strength tests according to the ISO standard and comprising repeated bending cycles, without there being any damage to the chip or the support.
These bending cycles are of two types:
500 bends along an axis X parallel to the longitudinal edges and situated equidistant therefrom;
500 bends along an axis Y parallel to the transverse edges and situated equidistant therefrom.
Also in a known manner, the standardised position of the mini-card MC in the card C is such that the mini-card is not situated equidistant from the two longitudinal edges 18 and 20. Thus, the longitudinal edge 26 of the mini-card MC connected to the support 10 by the top link B2 is closer to the adjacent longitudinal edge 18 of the support 10 than the longitudinal edge 28 of the mini-card MC connected to the support 10 by the bottom link B3.
A conventional method of manufacturing the card consists of injecting the polymer plastic material intended to form the support 10 into a suitable mould. This injection makes it possible to form the card body as well as the mini-card and links simultaneously. Next, the various information that has to appear on the card is printed, then the support is varnished, and finally, it is put into a card.
The injection is such that the polymer material enters the mould by a so-called injection input I close to the front transverse edge 22 of the support 10 and the longitudinal edge 28 of the mini-card, carrying the bottom link B3.
The flow of material in the bottom link B3 is therefore directed from the card towards the mini-card; thus the chains of the polymer material are oriented in the bottom link in the direction of the mini-card. For this reason, during detachment of the mini-card, the breaking of the bottom link B3 takes place leaving a cut line going in towards the inside of the mini-card. On the contrary, the flow of material in the top link B2 is directed from the mini-card towards the card so that, during detachment of the mini-card, the breaking of the top link B2 takes place leaving a cut line going outwards from the mini-card, and this is greater the longer the base of the trapezium of the upper groove.
This poses a significant problem for the subsequent use of the mini-card in a connector. This is because the material jutting out beyond the mini-card interferes with the insertion of the mini-card into the connector with which it is intended to cooperate, which for its part is adjusted as close as possible to the standardised dimensions of the mini-card in order to provide correct and reliable contact of the contact areas of the mini-card with the contacts of the connector.